An ordered and stable silicon (Si) surface is most desirable for subsequent epitaxial growth of single crystal thin films on silicon for numerous device applications, e.g., ferroelectrics or high dielectric constant oxides for non-volatile and high density memory devices. It is pivotal to establish an ordered transition layer on Si surface, especially for subsequent growth of single crystal oxides, e.g. perovskites. Some reported successful growth of these oxides, such as BaO and BaTiO.sub.3 on Si(100) was based on a BaSi.sub.2 (cubic) template by depositing one fourth monolayer of Ba on Si(100) using reactive epitaxy at temperatures greater than 850.degree. C. See for example: R. McKee, et al., Appl. Phys. Lett. 59(7), pp, 782-784, (Aug. 12, 1991); R. McKee, et al., Appl. Phys. Lett. 63(20), pp, 2818-2820, (Nov. 15, 1993); R. McKee et al., Mat. Res. Soc. Symp. Proc., Vol. 21, pp. 131-135, (1991); U.S. Pat. No. 5,225,01, issued Jul. 6, 1993, entitled "Process for Depositing an Oxide Epitaxially onto a Silicon Substrate and Structures Prepared with the Process"; and U.S. Pat. No. 5,482,003, issued Jan. 9, 1996, entitled "Process for Depositing Epitaxial Alkaline Earth Oxide onto a Substrate and Structures Prepared with the Process". The high temperature requirement for the Molecular Beam Epitaxy surface preparation and template (e.g. BaSi.sub.2) formation truly makes the above mentioned process a high temperature process. The major problems are that this high temperature process requires a much higher thermal budget, promotes diffusion in the structure, and often is not desirable or affordable.
It is highly desirable, therefore, to have a Molecular Beam Epitaxy compatible low temperature process that is simple to perform and that provides an ordered wafer surface for subsequent thin film epitaxy.
It is a purpose of the present invention to provide a new and improved method of preparing crystalline alkaline earth metal oxides on a Si substrate.
It is another purpose of the present invention to provide a new and improved method of preparing crystalline alkaline earth metal oxides on a Si substrate using Molecular Beam Epitaxy compatible low temperatures.
It is still another purpose of the present invention to provide a new and improved method of preparing crystalline alkaline earth metal oxides on a Si substrate using a simplified method that requires very little monitoring during the process.
It is a further purpose of the present invention to provide a new and improved method of preparing crystalline alkaline earth metal oxides on a Si substrate which provides an ordered wafer surface.
It is still a further purpose of the present invention to provide a new and improved method of preparing crystalline alkaline earth metal oxides on a Si substrate which does not unnecessarily complicate subsequent process steps.